Obviously I can't say how these actors will play their roles. Hopefully they are great.
The only ones I knew beforehand were Sean Bean & Lena Headey. I would not say Rosamund Pike is, right now, more obscure than they were in 2011. It's not like Issac Hempstead-Wright, Kit Harrington & Emilia Clarke were any better known than the Emond's Field crew.
And while their budgets clearly were expanded as the show grew in popularity, at the outset, Game of Thrones had enough to do what they needed.
My concern is they might go the "Winter Dragon" route too often and cheap out on things that would require major VFX, of which there are more in "Eye of the World" than there were in "A Game of Thrones". Lews Therin's death, and the battle in Tarwin's Gap strike me as potentially more expensive than anything Game of Thrones tried in Season 1. Not sure how the One Power will play out with Moiraine's uses.
“Tolerance is the virtue of the man without convictions.” GK Chesteron
Inde muagdhe Aes Sedai misain ye!
Deus Vult!
*MySmiley*